Legally, a work is copyrighted the moment you create it. So, even if someone steals your beat, you can still sue and win (even if you didn't copyright your beat with the library of congress). HOWEVER, you must:
1. Find a musicologist that will testify that the beat is "significantly similar" to yours and
2. Prove that whoever wrote the beat had ACCESS to your track in order to rip it off (like an email where you sent it to him)
I've had hit sh!t ripped before and it does not feel good. On the other hand, I've had people hire to copy beats they didn't have the money to license and have made money from it. It might happen to you, but don't worry about it. Just keep writing slammin' beatz and you'll get noticed, leaving all the haterz in the dust